In recent years, as one of the thermal spray methods, the cold spray method has received attention that sprays material powder at high temperature and high velocity onto a substrate, thereby depositing the material powder to coat the substrate. In the cold spray method, the material to be a film is sprayed together with an inert gas heated to a temperature of not more than the melting point or softening point of the material powder through a convergent-divergent (Laval) nozzle to impinge on the substrate while remaining in a solid phase, thereby forming the film on a surface of the substrate. This produces a metal film free of phase transformation and with reduced oxidization.
Conventionally, as the cold spray method, a technique is disclosed in which a substrate is temperature-controlled to a predetermined temperature to be sprayed with material powder (for example, see Patent Literature 1), and another technique is disclosed in which a substrate and/or an inert gas is temperature-controlled to form a metal film (for example, Patent Literature 2).